Determining and Adapting to Changes in Microphone Performance of Playback Devices

ABSTRACT

Systems and methods for determining and adapting to changes in microphone performance of playback devices are disclosed herein. In one example, an audio input is received at an array of individual microphones of a network microphone device. Output microphone signals are generated from each of the individual microphones based on the audio input. The output microphone signals are analyzed to detect a trigger event. After detecting the trigger event, the output microphone signals are compared to detect aberrant behavior of one or more of the microphones. Optionally, corrective actions can be taken or suggested based on the detection of aberrant behavior of one or more microphones.

FIELD OF THE DISCLOSURE

The disclosure is related to consumer goods and, more particularly, to methods, systems, products, features, services, and other elements directed to determining and adapting to microphone performance in playback devices or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loud setting were limited until in 2003, when SONOS, Inc. filed for one of its first patent applications, entitled “Method for Synchronizing Audio Playback between Multiple Networked Devices,” and began offering a media playback system for sale in 2005. The Sonos Wireless HiFi System enables people to experience music from many sources via one or more networked playback devices. Through a software control application installed on a smartphone, tablet, or computer, one can play what he or she wants in any room that has a networked playback device. Additionally, using the controller, for example, different songs can be streamed to each room with a playback device, rooms can be grouped together for synchronous playback, or the same song can be heard in all rooms synchronously.

Given the ever-growing interest in digital media, there continues to be a need to develop consumer-accessible technologies to further enhance the listening experience.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technology may be better understood with regard to the following description, appended claims, and accompanying drawings where:

FIG. 1 shows a media playback system in which certain embodiments may be practiced;

FIG. 2A is a functional block diagram of an example playback device;

FIG. 2B is an isometric diagram of an example playback device that includes a network microphone device;

FIGS. 3A, 3B, 3C, 3D, and 3E are diagrams showing example zones and zone groups in accordance with aspects of the disclosure;

FIG. 4 is a functional block diagram of an example controller device in accordance with aspects of the disclosure;

FIGS. 4A and 4B are controller interfaces in accordance with aspects of the disclosure;

FIG. 5A is a functional block diagram of an example network microphone device in accordance with aspects of the disclosure;

FIG. 5B is a diagram of an example voice input in accordance with aspects of the disclosure;

FIG. 6 is a functional block diagram of example remote computing device(s) in accordance with aspects of the disclosure;

FIG. 7A is a schematic diagram of an example network system in accordance with aspects of the disclosure;

FIG. 7B is an example message flow implemented by the example network system of FIG. 7A in accordance with aspects of the disclosure;

FIG. 8 is a functional flow diagram of an example microphone evaluation in accordance with aspects of the disclosure;

FIGS. 9A-9C illustrate example frequency responses obtained during microphone evaluation; and

FIG. 10 is an example method of a network microphone device evaluating individual microphones of an array to detect aberrant behavior.

The drawings are for the purpose of illustrating example embodiments, but those of ordinary skill in the art will understand that the technology disclosed herein is not limited to the arrangements and/or instrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

Voice control can be beneficial for a “smart” home having smart appliances and related devices, such as wireless illumination devices, home-automation devices (e.g., thermostats, door locks, etc.), and audio playback devices. In some implementations, networked microphone devices may be used to control smart home devices. A network microphone device (NMD) will typically include a microphone for receiving voice inputs. The network microphone device can forward voice inputs to a voice assistant service (VAS). A traditional VAS may be a remote service implemented by cloud servers to process voice inputs. A VAS may process a voice input to determine an intent of the voice input. Based on the response, the NMD may cause one or more smart devices to perform an action. For example, the NMD may instruct an illumination device to turn on/off based on the response to the instruction from the VAS.

A voice input detected by an NMD will typically include a wake word followed by an utterance containing a user request. The wake word is typically a predetermined word or phrase used to “wake up” and invoke the VAS for interpreting the intent of the voice input. For instance, in querying the AMAZON® VAS, a user might speak the wake word “Alexa.” Other examples include “Ok, Google” for invoking the GOOGLE® VAS and “Hey, Siri” for invoking the APPLE® VAS, or “Hey, Sonos” for a VAS offered by SONOS®.

In operation, an NMD listens for a user request or command accompanying a wake word in the voice input. In some instances, the user request may include a command to control a third-party device, such as a thermostat (e.g., NEST® thermostat), an illumination device (e.g., a PHILIPS HUE® lighting device), or a media playback device (e.g., a Sonos® playback device). For example, a user might speak the wake word “Alexa” followed by the utterance “set the thermostat to 68 degrees” to set the temperature in a home using the Amazon® VAS. A user might speak the same wake word followed by the utterance “turn on the living room” to turn on illumination devices in a living room area of the home. The user may similarly speak a wake word followed by a request to play a particular song, an album, or a playlist of music on a playback device in the home.

An NMD can include an array of individual microphones. In operation, the NMD receives audio data from each of the individual microphones, which is then combined and processed to assess whether a wake word has been detected. If the wake word has been detected, the NMD can pass subsequent audio input to a VAS for further processing. If one or more of the individual microphones suffers performance issues, the functionality of the network microphone device may be impaired. Individual microphones may be impaired due to hardware problems with the microphone itself (e.g., damage or defect to one or more of the components of the microphone) or due to obstructions blocking audio from reaching the microphone (e.g., dust blocking a microphone port in the NMD, a piece of furniture partially blocking one of the microphones, etc.). Problems with one or more of the individual microphones can lead to aberrant audio signals, for example audio signals exhibiting excess noise, distortion, or other artifacts that can deleteriously affect downstream processing. This deterioration in audio quality may lead to poor performance at the VAS, for example, inability to accurately capture and respond to voice commands.

Embodiments of the present technology enable evaluation of the audio input received at individual microphones of an NMD to determine whether one or more of the microphones are performing sub-optimally, or not at all. For example, by comparing the performance data for each microphone in the array, the system can identify aberrant behavior by one or more of the microphones. In some embodiments, the system calculates a mean or median value for the frequency responses of all the microphones, and then evaluates the frequency response of each individual microphone against the median value. In other embodiments, the frequency response of each individual microphone can be compared against the mean or other averaged value. If the frequency response for any given microphone deviates from the median by more than a threshold amount, then the system can identify that microphone as performing aberrantly. As one example, individual microphones can be identified as aberrant if the frequency response deviates from the median frequency response by more than two times the median absolute deviation per frequency bin for at least 75% of the spectrum. Other microphone performance data, thresholds, and means or medians can be used, as described in more detail below.

In some embodiments, the NMD provides microphone performance data (e.g., frequency responses for each microphone) to a remote computing device for evaluation. To protect user privacy, it can be useful to rely only on microphone performance data that does not reveal the original audio content (e.g., the content of recorded speech input). For example, the NMD can derive the microphone performance data from audio content in a manner that renders the original audio signal indecipherable if one only has access to the microphone performance data. By limiting the microphone performance data to frequency-domain information that is averaged over many sampling frames, rather than time-domain information, the NMD can render the original audio content indecipherable via the microphone performance data. In operation, the NMD can gather microphone performance data (e.g., frequency responses for each microphone) and send this data to one or more computing devices of a remote evaluator for evaluation and comparison. The remote evaluator can then evaluate the microphone performance data to identify any problematic microphones. As such, in some embodiments, the system can detect problems with one or more microphones in the NMD without infringing on user privacy by sending recorded audio content to the remote evaluator.

Optionally, the system takes corrective measures in response to detecting aberrant performance of a microphone. For example, the NMD can modify its operation to accommodate the defective microphone (e.g., disregarding input from the defective microphone, modifying the beam-forming algorithm to compensate for the defective microphone, etc.). Additionally or alternatively, the NMD can provide an alert to the user, manufacturer, or other entity, potentially with suggested corrective actions (e.g., instructing the user to reposition the NMD).

While some examples described herein may refer to functions performed by given actors such as “users,” “listeners,” and/or other entities, it should be understood that this is for purposes of explanation only. The claims should not be interpreted to require action by any such example actor unless explicitly required by the language of the claims themselves.

In the Figures, identical reference numbers identify generally similar, and/or identical, elements. Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular embodiments of the disclosed technology. Accordingly, other embodiments can have other details, dimensions, angles and features without departing from the spirit or scope of the disclosure. In addition, those of ordinary skill in the art will appreciate that further embodiments of the various disclosed technologies can be practiced without several of the details described below.

II. Example Operating Environment

FIG. 1 illustrates an example configuration of a media playback system 100 in which one or more embodiments disclosed herein may be implemented. The media playback system 100 as shown is associated with an example home environment having several rooms and spaces, such as for example, an office, a dining room, and a living room. Within these rooms and spaces, the media playback system 100 includes playback devices 102 (identified individually as playback devices 102 a-102 m), network microphone devices 103 (identified individually as “NMD(s)” 103 a-103 g), and controller devices 104 a and 104 b (collectively “controller devices 104”). The home environment may include other network devices, such as one or more smart illumination devices 108 and a smart thermostat 110.

The various playback, network microphone, and controller devices 102-104 and/or other network devices of the media playback system 100 may be coupled to one another via point-to-point connections and/or over other connections, which may be wired and/or wireless, via a LAN including a network router 106. For example, the playback device 102 j (designated as “Left”) may have a point-to-point connection with the playback device 102 a (designated as “Right”). In one embodiment, the Left playback device 102 j may communicate over the point-to-point connection with the Right playback device 102 a. In a related embodiment, the Left playback device 102 j may communicate with other network devices via the point-to-point connection and/or other connections via the LAN.

The network router 106 may be coupled to one or more remote computing device(s) 105 via a wide area network (WAN) 107. In some embodiments, the remote computing device(s) may be cloud servers. The remote computing device(s) 105 may be configured to interact with the media playback system 100 in various ways. For example, the remote computing device(s) may be configured to facilitate streaming and controlling playback of media content, such as audio, in the home environment. In one aspect of the technology described in greater detail below, the remote computing device(s) 105 are configured to provide a first VAS 160 for the media playback system 100.

In some embodiments, one or more of the playback devices 102 may include an on-board (e.g., integrated) network microphone device. For example, the playback devices 102 a-e include corresponding NMDs 103 a-e, respectively. Playback devices that include network microphone devices may be referred to herein interchangeably as a playback device or a network microphone device unless indicated otherwise in the description.

In some embodiments, one or more of the NMDs 103 may be a stand-alone device. For example, the NMDs 103 f and 103 g may be stand-alone network microphone devices. A stand-alone network microphone device may omit components typically included in a playback device, such as a speaker or related electronics. In such cases, a stand-alone network microphone device may not produce audio output or may produce limited audio output (e.g., relatively low-quality audio output compared to a playback device).

In use, a network microphone device may receive and process voice inputs from a user in its vicinity. For example, a network microphone device may capture a voice input upon detection of the user speaking the input. In the illustrated example, the NMD 103 a of the playback device 102 a in the Living Room may capture the voice input of a user in its vicinity. In some instances, other network microphone devices (e.g., the NMDs 103 b and 103 f) in the vicinity of the voice input source (e.g., the user) may also detect the voice input. In such instances, network microphone devices may arbitrate between one another to determine which device(s) should capture and/or process the detected voice input. Examples for selecting and arbitrating between network microphone devices may be found, for example, in U.S. application Ser. No. 15/438,749 filed Feb. 21, 2017, and titled “Voice Control of a Media Playback System,” which is incorporated herein by reference in its entirety.

In certain embodiments, a network microphone device may be assigned to a playback device that may not include a network microphone device. For example, the NMD 103 f may be assigned to the playback devices 102 i and/or 1021 in its vicinity. In a related example, a network microphone device may output audio through a playback device to which it is assigned. Additional details regarding associating network microphone devices and playback devices as designated or default devices may be found, for example, in previously referenced U.S. patent application Ser. No. 15/438,749.

Further aspects relating to the different components of the example media playback system 100 and how the different components may interact to provide a user with a media experience may be found in the following sections. While discussions herein may generally refer to the example media playback system 100, technologies described herein are not limited to applications within, among other things, the home environment as shown in FIG. 1. For instance, the technologies described herein may be useful in other home environment configurations comprising more or fewer of any of the playback, network microphone, and/or controller devices 102-104. Additionally, the technologies described herein may be useful in environments where multi-zone audio may be desired, such as, for example, a commercial setting like a restaurant, mall or airport, a vehicle like a sports utility vehicle (SUV), bus or car, a ship or boat, an airplane, and so on.

a. Example Playback and Network Microphone Devices

By way of illustration, SONOS, Inc. presently offers (or has offered) for sale certain playback devices including a “PLAY:1,” “SONOS ONE” “PLAY:3,” “PLAY:5,” “PLAYBAR,” “PLAYBASE,” “CONNECT:AMP,” “CONNECT,” and “SUB.” Any other past, present, and/or future playback devices may additionally or alternatively be used to implement the playback devices of example embodiments disclosed herein. Additionally, it is understood that a playback device is not limited to the examples shown and described herein or to the SONOS product offerings. For example, a playback device may include a wired or wireless headphone. In another example, a playback device may include or interact with a docking station for personal mobile media playback devices. In yet another example, a playback device may be integral to another device or component such as a television, a lighting fixture, or some other device for indoor or outdoor use.

FIG. 2A is a functional block diagram illustrating certain aspects of a selected one of the playback devices 102 shown in FIG. 1. As shown, such a playback device may include a processor 212, software components 214, memory 216, audio processing components 218, audio amplifier(s) 220, speaker(s) 222, and a network interface 230 including wireless interface(s) 232 and wired interface(s) 234. In some embodiments, a playback device may not include the speaker(s) 222, but rather a speaker interface for connecting the playback device to external speakers. In certain embodiments, the playback device may include neither the speaker(s) 222 nor the audio amplifier(s) 220, but rather an audio interface for connecting a playback device to an external audio amplifier or audio-visual receiver.

A playback device may further include a user interface 236. The user interface 236 may facilitate user interactions independent of or in conjunction with one or more of the controller devices 104. In various embodiments, the user interface 236 includes one or more of physical buttons and/or graphical interfaces provided on touch sensitive screen(s) and/or surface(s), among other possibilities, for a user to directly provide input. The user interface 236 may further include one or more of lights and the speaker(s) to provide visual and/or audio feedback to a user.

In some embodiments, the processor 212 may be a clock-driven computing component configured to process input data according to instructions stored in the memory 216. The memory 216 may be a tangible computer-readable medium configured to store instructions executable by the processor 212. For example, the memory 216 may be data storage that can be loaded with one or more of the software components 214 executable by the processor 212 to achieve certain functions. In one example, the functions may involve a playback device retrieving audio data from an audio source or another playback device. In another example, the functions may involve a playback device sending audio data to another device on a network. In yet another example, the functions may involve pairing of a playback device with one or more other playback devices to create a multi-channel audio environment.

Certain functions may include or otherwise involve a playback device synchronizing playback of audio content with one or more other playback devices. During synchronous playback, a listener may not perceive time-delay differences between playback of the audio content by the synchronized playback devices. U.S. Pat. No. 8,234,395 filed Apr. 4, 2004, and titled “System and method for synchronizing operations among a plurality of independently clocked digital data processing devices,” which is hereby incorporated by reference in its entirety, provides in more detail some examples for audio playback synchronization among playback devices.

The audio processing components 218 may include one or more digital-to-analog converters (DAC), an audio preprocessing component, an audio enhancement component or a digital signal processor (DSP), and so on. In some embodiments, one or more of the audio processing components 218 may be a subcomponent of the processor 212. In one example, audio content may be processed and/or intentionally altered by the audio processing components 218 to produce audio signals. The produced audio signals may then be provided to the audio amplifier(s) 210 for amplification and playback through speaker(s) 212. Particularly, the audio amplifier(s) 210 may include devices configured to amplify audio signals to a level for driving one or more of the speakers 212. The speaker(s) 212 may include an individual transducer (e.g., a “driver”) or a complete speaker system involving an enclosure with one or more drivers. A particular driver of the speaker(s) 212 may include, for example, a subwoofer (e.g., for low frequencies), a mid-range driver (e.g., for middle frequencies), and/or a tweeter (e.g., for high frequencies). In some cases, each transducer in the one or more speakers 212 may be driven by an individual corresponding audio amplifier of the audio amplifier(s) 210. In addition to producing analog signals for playback, the audio processing components 208 may be configured to process audio content to be sent to one or more other playback devices for playback.

Audio content to be processed and/or played back by a playback device may be received from an external source, such as via an audio line-in input connection (e.g., an auto-detecting 3.5 mm audio line-in connection) or the network interface 230.

The network interface 230 may be configured to facilitate a data flow between a playback device and one or more other devices on a data network. As such, a playback device may be configured to receive audio content over the data network from one or more other playback devices in communication with a playback device, network devices within a local area network, or audio content sources over a wide area network such as the Internet. In one example, the audio content and other signals transmitted and received by a playback device may be transmitted in the form of digital packet data containing an Internet Protocol (IP)-based source address and IP-based destination addresses. In such a case, the network interface 230 may be configured to parse the digital packet data such that the data destined for a playback device is properly received and processed by the playback device.

As shown, the network interface 230 may include wireless interface(s) 232 and wired interface(s) 234. The wireless interface(s) 232 may provide network interface functions for a playback device to wirelessly communicate with other devices (e.g., other playback device(s), speaker(s), receiver(s), network device(s), control device(s) within a data network the playback device is associated with) in accordance with a communication protocol (e.g., any wireless standard including IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4G mobile communication standard, and so on). The wired interface(s) 234 may provide network interface functions for a playback device to communicate over a wired connection with other devices in accordance with a communication protocol (e.g., IEEE 802.3). While the network interface 230 shown in FIG. 2A includes both wireless interface(s) 232 and wired interface(s) 234, the network interface 230 may in some embodiments include only wireless interface(s) or only wired interface(s).

As discussed above, a playback device may include a network microphone device, such as one of the NMDs 103 shown in FIG. 1. A network microphone device may share some or all the components of a playback device, such as the processor 212, the memory 216, the microphone(s) 224, etc. In other examples, a network microphone device includes components that are dedicated exclusively to operational aspects of the network microphone device. For example, a network microphone device may include far-field microphones and/or voice processing components, which in some instances a playback device may not include. But in some embodiments, a playback device may contain the same or similar far-field microphones and/or voice processing components as a network microphone device. In another example, a network microphone device may include a touch-sensitive button for enabling/disabling a microphone.

FIG. 2B is an isometric diagram showing an example playback device 202 incorporating a network microphone device (NMD). The playback device 202 has an upper portion 237 at the top of the device comprising a plurality of ports, holes, or apertures 227 in the upper portion 237 that allow sound to pass through to one or more individual microphones 224 (not shown in FIG. 2B) positioned within the device 202. For example, a plurality of microphones 224 can be arranged in an array configured to receive sound and produce electrical signals based on the received sound. In some embodiments, the playback device 202 is configured to analyze and/or compare electrical signals from individual microphones 224 of the array to detect aberrant behavior by one or more of the microphones.

b. Example Playback Device Configurations

FIGS. 3A-3E show example configurations of playback devices in zones and zone groups. Referring first to FIG. 3E, in one example, a single playback device may belong to a zone. For example, the playback device 102 c in the Balcony may belong to Zone A. In some implementations described below, multiple playback devices may be “bonded” to form a “bonded pair” which together form a single zone. For example, the playback device 102 f named Nook in FIG. 1 may be bonded to the playback device 102 g named Wall to form Zone B. Bonded playback devices may have different playback responsibilities (e.g., channel responsibilities). In another implementation described below, multiple playback devices may be merged to form a single zone. For example, the playback device 102 d named Office may be merged with the playback device 102 m named Window to form a single Zone C. The merged playback devices 102 d and 102 m may not be specifically assigned different playback responsibilities. That is, the merged playback devices 102 d and 102 m may, aside from playing audio content in synchrony, each play audio content as they would if they were not merged.

Each zone in the media playback system 100 may be provided for control as a single user interface (UI) entity. For example, Zone A may be provided as a single entity named Balcony. Zone C may be provided as a single entity named Office. Zone B may be provided as a single entity named Shelf.

In various embodiments, a zone may take on the name of one of the playback device(s) belonging to the zone. For example, Zone C may take on the name of the Office device 102 d (as shown). In another example, Zone C may take on the name of the Window device 102 m. In a further example, Zone C may take on a name that is some combination of the Office device 102 d and Window device 102 m. The name that is chosen may be selected by user. In some embodiments, a zone may be given a name that is different than the device(s) belonging to the zone. For example, Zone B is named Shelf but none of the devices in Zone B have this name.

Playback devices that are bonded may have different playback responsibilities, such as responsibilities for certain audio channels. For example, as shown in FIG. 3A, the Nook and Wall devices 102 f and 102 g may be bonded so as to produce or enhance a stereo effect of audio content. In this example, the Nook playback device 102 f may be configured to play a left channel audio component, while the Wall playback device 102 g may be configured to play a right channel audio component. In some implementations, such stereo bonding may be referred to as “pairing.”

Additionally, bonded playback devices may have additional and/or different respective speaker drivers. As shown in FIG. 3B, the playback device 102 b named Front may be bonded with the playback device 102 k named SUB. The Front device 102 b may render a range of mid to high frequencies and the SUB device 102 k may render low frequencies as, e.g., a subwoofer. When un-bonded, the Front device 102 b may render a full range of frequencies. As another example, FIG. 3C shows the Front and SUB devices 102 b and 102 k further bonded with Right and Left playback devices 102 a and 102 k, respectively. In some implementations, the Right and Left devices 102 a and 102 k may form surround or “satellite” channels of a home theatre system. The bonded playback devices 102 a, 102 b, 102 j, and 102 k may form a single Zone D (FIG. 3E).

Playback devices that are merged may not have assigned playback responsibilities, and may each render the full range of audio content the respective playback device is capable of. Nevertheless, merged devices may be represented as a single UI entity (i.e., a zone, as discussed above). For instance, the playback device 102 d and 102 m in the Office have the single UI entity of Zone C. In one embodiment, the playback devices 102 d and 102 m may each output the full range of audio content each respective playback device 102 d and 102 m are capable of, in synchrony.

In some embodiments, a stand-alone network microphone device may be in a zone by itself. For example, the NMD 103 g in FIG. 1 named Ceiling may be Zone E. A network microphone device may also be bonded or merged with another device so as to form a zone. For example, the NMD device 103 f named Island may be bonded with the playback device 102 i Kitchen, which together form Zone G, which is also named Kitchen. Additional details regarding associating network microphone devices and playback devices as designated or default devices may be found, for example, in previously referenced U.S. patent application Ser. No. 15/438,749. In some embodiments, a stand-alone network microphone device may not be associated with a zone.

Zones of individual, bonded, and/or merged devices may be grouped to form a zone group. For example, referring to FIG. 3E, Zone A may be grouped with Zone B to form a zone group that includes the two zones. As another example, Zone A may be grouped with one or more other Zones C-I. The Zones A-I may be grouped and ungrouped in numerous ways. For example, three, four, five, or more (e.g., all) of the Zones A-I may be grouped. When grouped, the zones of individual and/or bonded playback devices may play back audio in synchrony with one another, as described in previously referenced U.S. Pat. No. 8,234,395. Playback devices may be dynamically grouped and ungrouped to form new or different groups that synchronously play back audio content.

In various implementations, the zones in an environment may be the default name of a zone within the group or a combination of the names of the zones within a zone group, such as Dining Room+Kitchen, as shown in FIG. 3E. In some embodiments, a zone group may be given a unique name selected by a user, such as Nick's Room, as also shown in FIG. 3E.

Referring again to FIG. 2A, certain data may be stored in the memory 216 as one or more state variables that are periodically updated and used to describe the state of a playback zone, the playback device(s), and/or a zone group associated therewith. The memory 216 may also include the data associated with the state of the other devices of the media system, and shared from time to time among the devices so that one or more of the devices have the most recent data associated with the system.

In some embodiments, the memory may store instances of various variable types associated with the states. Variables instances may be stored with identifiers (e.g., tags) corresponding to type. For example, certain identifiers may be a first type “a1” to identify playback device(s) of a zone, a second type “b1” to identify playback device(s) that may be bonded in the zone, and a third type “c1” to identify a zone group to which the zone may belong. As a related example, in FIG. 1, identifiers associated with the Balcony may indicate that the Balcony is the only playback device of a particular zone and not in a zone group. Identifiers associated with the Living Room may indicate that the Living Room is not grouped with other zones but includes bonded playback devices 102 a, 102 b, 102 j, and 102 k. Identifiers associated with the Dining Room may indicate that the Dining Room is part of Dining Room+Kitchen group and that devices 103 f and 102 i are bonded. Identifiers associated with the Kitchen may indicate the same or similar information by virtue of the Kitchen being part of the Dining Room+Kitchen zone group. Other example zone variables and identifiers are described below.

In yet another example, the media playback system 100 may store and use variables or identifiers representing other associations of zones and zone groups, such as identifiers associated with Areas, as shown in FIG. 3. An area may involve a cluster of zone groups and/or zones not within a zone group. For instance, FIG. 3E shows a first area named Front Area and a second area named Back Area. The Front Area includes zones and zone groups of the Balcony, Living Room, Dining Room, Kitchen, and Bathroom. The Back Area includes zones and zone groups of the Bathroom, Nick's Room, the Bedroom, and the Office. In one aspect, an Area may be used to invoke a cluster of zone groups and/or zones that share one or more zones and/or zone groups of another cluster. In another aspect, this differs from a zone group, which does not share a zone with another zone group. Further examples of techniques for implementing Areas may be found, for example, in U.S. application Ser. No. 15/682,506 filed Aug. 21, 2017 and titled “Room Association Based on Name,” and U.S. Pat. No. 8,483,853 filed Sep. 11, 2007, and titled “Controlling and manipulating groupings in a multi-zone media system.” U.S. application Ser. No. 15/682,506 and U.S. Pat. No. 8,483,853 are both incorporated herein by reference in their entirety. In some embodiments, the media playback system 100 may not implement Areas, in which case the system may not store variables associated with Areas.

The memory 216 may be further configured to store other data. Such data may pertain to audio sources accessible by a playback device or a playback queue that the playback device (or some other playback device(s)) may be associated with. In embodiments described below, the memory 216 is configured to store a set of command data for selecting a particular VAS, such as the VAS 160, when processing voice inputs.

During operation, one or more playback zones in the environment of FIG. 1 may each be playing different audio content. For instance, the user may be grilling in the Balcony zone and listening to hip hop music being played by the playback device 102 c while another user may be preparing food in the Kitchen zone and listening to classical music being played by the playback device 102 i. In another example, a playback zone may play the same audio content in synchrony with another playback zone. For instance, the user may be in the Office zone where the playback device 102 d is playing the same hip-hop music that is being playing by playback device 102 c in the Balcony zone. In such a case, playback devices 102 c and 102 d may be playing the hip-hop in synchrony such that the user may seamlessly (or at least substantially seamlessly) enjoy the audio content that is being played out-loud while moving between different playback zones. Synchronization among playback zones may be achieved in a manner similar to that of synchronization among playback devices, as described in previously referenced U.S. Pat. No. 8,234,395.

As suggested above, the zone configurations of the media playback system 100 may be dynamically modified. As such, the media playback system 100 may support numerous configurations. For example, if a user physically moves one or more playback devices to or from a zone, the media playback system 100 may be reconfigured to accommodate the change(s). For instance, if the user physically moves the playback device 102 c from the Balcony zone to the Office zone, the Office zone may now include both the playback devices 102 c and 102 d. In some cases, the use may pair or group the moved playback device 102 c with the Office zone and/or rename the players in the Office zone using, e.g., one of the controller devices 104 and/or voice input. As another example, if one or more playback devices 102 are moved to a particular area in the home environment that is not already a playback zone, the moved playback device(s) may be renamed or associated with a playback zone for the particular area.

Further, different playback zones of the media playback system 100 may be dynamically combined into zone groups or split up into individual playback zones. For example, the Dining Room zone and the Kitchen zone may be combined into a zone group for a dinner party such that playback devices 102 i and 102 l may render audio content in synchrony. As another example, bonded playback devices 102 in the Living Room zone may be split into (i) a television zone and (ii) a separate listening zone. The television zone may include the Front playback device 102 b. The listening zone may include the Right, Left, and SUB playback devices 102 a, 102 j, and 102 k, which may be grouped, paired, or merged, as described above. Splitting the Living Room zone in such a manner may allow one user to listen to music in the listening zone in one area of the living room space, and another user to watch the television in another area of the living room space. In a related example, a user may implement either of the NMD 103 a or 103 b to control the Living Room zone before it is separated into the television zone and the listening zone. Once separated, the listening zone may be controlled, for example, by a user in the vicinity of the NMD 103 a, and the television zone may be controlled, for example, by a user in the vicinity of the NMD 103 b. As described above, however, any of the NMDs 103 may be configured to control the various playback and other devices of the media playback system 100.

c. Example Controller Devices

FIG. 4 is a functional block diagram illustrating certain aspects of a selected one of the controller devices 104 of the media playback system 100 of FIG. 1. Such controller devices may also be referred to as a controller. The controller device shown in FIG. 4 may include components that are generally similar to certain components of the network devices described above, such as a processor 412, memory 416, microphone(s) 424, and a network interface 430. In one example, a controller device may be a dedicated controller for the media playback system 100. In another example, a controller device may be a network device on which media playback system controller application software may be installed, such as for example, an iPhone™, iPad™ or any other smart phone, tablet or network device (e.g., a networked computer such as a PC or Mac™).

The memory 416 of a controller device may be configured to store controller application software and other data associated with the media playback system 100 and a user of the system 100. The memory 416 may be loaded with one or more software components 414 executable by the processor 412 to achieve certain functions, such as facilitating user access, control, and configuration of the media playback system 100. A controller device communicates with other network devices over the network interface 430, such as a wireless interface, as described above.

In one example, data and information (e.g., such as a state variable) may be communicated between a controller device and other devices via the network interface 430. For instance, playback zone and zone group configurations in the media playback system 100 may be received by a controller device from a playback device, a network microphone device, or another network device, or transmitted by the controller device to another playback device or network device via the network interface 406. In some cases, the other network device may be another controller device.

Playback device control commands such as volume control and audio playback control may also be communicated from a controller device to a playback device via the network interface 430. As suggested above, changes to configurations of the media playback system 100 may also be performed by a user using the controller device. The configuration changes may include adding/removing one or more playback devices to/from a zone, adding/removing one or more zones to/from a zone group, forming a bonded or merged player, separating one or more playback devices from a bonded or merged player, among others.

The user interface(s) 440 of a controller device may be configured to facilitate user access and control of the media playback system 100, by providing controller interface(s) such as the controller interfaces 440 a and 440 b shown in FIGS. 4A and 4B, respectively, which may be referred to collectively as the controller interface 440. Referring to FIGS. 4A and 4B together, the controller interface 440 includes a playback control region 442, a playback zone region 443, a playback status region 444, a playback queue region 446, and a sources region 448. The user interface 400 as shown is just one example of a user interface that may be provided on a network device such as the controller device shown in FIG. 3 and accessed by users to control a media playback system such as the media playback system 100. Other user interfaces of varying formats, styles, and interactive sequences may alternatively be implemented on one or more network devices to provide comparable control access to a media playback system.

The playback control region 442 (FIG. 4A) may include selectable (e.g., by way of touch or by using a cursor) icons to cause playback devices in a selected playback zone or zone group to play or pause, fast forward, rewind, skip to next, skip to previous, enter/exit shuffle mode, enter/exit repeat mode, enter/exit cross fade mode. The playback control region 442 may also include selectable icons to modify equalization settings, and playback volume, among other possibilities.

The playback zone region 443 (FIG. 4B) may include representations of playback zones within the media playback system 100. The playback zones regions may also include representation of zone groups, such as the Dining Room+Kitchen zone group, as shown. In some embodiments, the graphical representations of playback zones may be selectable to bring up additional selectable icons to manage or configure the playback zones in the media playback system, such as a creation of bonded zones, creation of zone groups, separation of zone groups, and renaming of zone groups, among other possibilities.

For example, as shown, a “group” icon may be provided within each of the graphical representations of playback zones. The “group” icon provided within a graphical representation of a particular zone may be selectable to bring up options to select one or more other zones in the media playback system to be grouped with the particular zone. Once grouped, playback devices in the zones that have been grouped with the particular zone will be configured to play audio content in synchrony with the playback device(s) in the particular zone. Analogously, a “group” icon may be provided within a graphical representation of a zone group. In this case, the “group” icon may be selectable to bring up options to deselect one or more zones in the zone group to be removed from the zone group. Other interactions and implementations for grouping and ungrouping zones via a user interface such as the user interface 400 are also possible. The representations of playback zones in the playback zone region 443 (FIG. 4B) may be dynamically updated as playback zone or zone group configurations are modified.

The playback status region 444 (FIG. 4A) may include graphical representations of audio content that is presently being played, previously played, or scheduled to play next in the selected playback zone or zone group. The selected playback zone or zone group may be visually distinguished on the user interface, such as within the playback zone region 443 and/or the playback status region 444. The graphical representations may include track title, artist name, album name, album year, track length, and other relevant information that may be useful for the user to know when controlling the media playback system via the user interface 440.

The playback queue region 446 may include graphical representations of audio content in a playback queue associated with the selected playback zone or zone group. In some embodiments, each playback zone or zone group may be associated with a playback queue containing information corresponding to zero or more audio items for playback by the playback zone or zone group. For instance, each audio item in the playback queue may comprise a uniform resource identifier (URI), a uniform resource locator (URL) or some other identifier that may be used by a playback device in the playback zone or zone group to find and/or retrieve the audio item from a local audio content source or a networked audio content source, possibly for playback by the playback device.

In one example, a playlist may be added to a playback queue, in which case information corresponding to each audio item in the playlist may be added to the playback queue. In another example, audio items in a playback queue may be saved as a playlist. In a further example, a playback queue may be empty, or populated but “not in use” when the playback zone or zone group is playing continuously streaming audio content, such as Internet radio that may continue to play until otherwise stopped, rather than discrete audio items that have playback durations. In an alternative embodiment, a playback queue can include Internet radio and/or other streaming audio content items and be “in use” when the playback zone or zone group is playing those items. Other examples are also possible.

When playback zones or zone groups are “grouped” or “ungrouped,” playback queues associated with the affected playback zones or zone groups may be cleared or re-associated. For example, if a first playback zone including a first playback queue is grouped with a second playback zone including a second playback queue, the established zone group may have an associated playback queue that is initially empty, that contains audio items from the first playback queue (such as if the second playback zone was added to the first playback zone), that contains audio items from the second playback queue (such as if the first playback zone was added to the second playback zone), or a combination of audio items from both the first and second playback queues. Subsequently, if the established zone group is ungrouped, the resulting first playback zone may be re-associated with the previous first playback queue, or be associated with a new playback queue that is empty or contains audio items from the playback queue associated with the established zone group before the established zone group was ungrouped. Similarly, the resulting second playback zone may be re-associated with the previous second playback queue, or be associated with a new playback queue that is empty, or contains audio items from the playback queue associated with the established zone group before the established zone group was ungrouped. Other examples are also possible.

With reference still to FIGS. 4A and 4B, the graphical representations of audio content in the playback queue region 446 (FIG. 4B) may include track titles, artist names, track lengths, and other relevant information associated with the audio content in the playback queue. In one example, graphical representations of audio content may be selectable to bring up additional selectable icons to manage and/or manipulate the playback queue and/or audio content represented in the playback queue. For instance, a represented audio content may be removed from the playback queue, moved to a different position within the playback queue, or selected to be played immediately, or after any currently playing audio content, among other possibilities. A playback queue associated with a playback zone or zone group may be stored in a memory on one or more playback devices in the playback zone or zone group, on a playback device that is not in the playback zone or zone group, and/or some other designated device. Playback of such a playback queue may involve one or more playback devices playing back media items of the queue, perhaps in sequential or random order.

The sources region 448 may include graphical representations of selectable audio content sources and selectable voice assistants associated with a corresponding VAS. The VASes may be selectively assigned. In some examples, multiple VASes, such as AMAZON's ALEXA® and another voice service, may be invokable by the same network microphone device. In some embodiments, a user may assign a VAS exclusively to one or more network microphone devices. For example, a user may assign the first VAS 160 to one or both of the NMDs 102 a and 102 b in the Living Room shown in FIG. 1, and a second VAS to the NMD 103 f in the Kitchen. Other examples are possible.

d. Example Audio Content Sources

The audio sources in the sources region 448 may be audio content sources from which audio content may be retrieved and played by the selected playback zone or zone group. One or more playback devices in a zone or zone group may be configured to retrieve playback audio content (e.g., according to a corresponding URI or URL for the audio content) from a variety of available audio content sources. In one example, audio content may be retrieved by a playback device directly from a corresponding audio content source (e.g., a line-in connection). In another example, audio content may be provided to a playback device over a network via one or more other playback devices or network devices.

Example audio content sources may include a memory of one or more playback devices in a media playback system such as the media playback system 100 of FIG. 1, local music libraries on one or more network devices (such as a controller device, a network-enabled personal computer, or a networked-attached storage (NAS), for example), streaming audio services providing audio content via the Internet (e.g., the cloud), or audio sources connected to the media playback system via a line-in input connection on a playback device or network devise, among other possibilities.

In some embodiments, audio content sources may be regularly added or removed from a media playback system such as the media playback system 100 of FIG. 1. In one example, an indexing of audio items may be performed whenever one or more audio content sources are added, removed or updated. Indexing of audio items may involve scanning for identifiable audio items in all folders/directory shared over a network accessible by playback devices in the media playback system, and generating or updating an audio content database containing metadata (e.g., title, artist, album, track length, among others) and other associated information, such as a URI or URL for each identifiable audio item found. Other examples for managing and maintaining audio content sources may also be possible.

e. Example Network Microphone Devices

FIG. 5A is a functional block diagram showing additional features of one or more of the NMDs 103 in accordance with aspects of the disclosure. The network microphone device shown in FIG. 5A may include components that are generally similar to certain components of network microphone devices described above, such as the processor 212 (FIG. 1), network interface 230 (FIG. 2A), microphone(s) 224, and the memory 216. Although not shown for purposes of clarity, a network microphone device may include other components, such as speakers, amplifiers, signal processors, as discussed above.

The microphone(s) 224 may be a plurality (e.g., an array) of microphones arranged to detect sound in the environment of the network microphone device. In one example, the microphone(s) 224 may be arranged to detect audio from one or more directions relative to the network microphone device. The microphone(s) 224 may be sensitive to a portion of a frequency range. In one example, a first subset of the microphone(s) 224 may be sensitive to a first frequency range, while a second subset of the microphone(s) 224 may be sensitive to a second frequency range. The microphone(s) 224 may further be arranged to capture location information of an audio source (e.g., voice, audible sound) and/or to assist in filtering background noise. Notably, in some embodiments the microphone(s) 224 may have a single microphone rather than a plurality of microphones.

A network microphone device may further include beam former components 551, acoustic echo cancellation (AEC) components 552, voice activity detector components 553, wake word detector components 554, a lookback buffer 560, and microphone evaluator components 562. In various embodiments, one or more of the components 551-556, and 562 may be a subcomponent of the processor 512. As described in more detail below, the lookback buffer 560 can be a physical memory storage used to temporarily store data. The data in the lookback buffer 560 can be continuously overwritten with new data, for example as in a ring buffer.

The beamforming and AEC components 551 and 552 are configured to detect an audio signal and determine aspects of voice input within the detect audio, such as the direction, amplitude, frequency spectrum, etc. For example, the beamforming and AEC components 551 and 552 may be used in a process to determine an approximate distance between a network microphone device and a user speaking to the network microphone device. In another example, a network microphone device may detective a relative proximity of a user to another network microphone device in a media playback system.

The voice activity detector activity components 553 are configured to work closely with the beamforming and AEC components 551 and 552 to capture sound from directions where voice activity is detected. Potential speech directions can be identified by monitoring metrics which distinguish speech from other sounds. Such metrics can include, for example, energy within the speech band relative to background noise and entropy within the speech band, which is measure of spectral structure. Speech typically has a lower entropy than most common background noise.

The wake-word detector components 554 are configured to monitor and analyze received audio to determine if any wake words are present in the audio. The wake-word detector components 554 may analyze the received audio using a wake word detection algorithm. In some embodiments, the received audio is stored in the lookback buffer 560 for detection via the wake-word detector components 554. If the wake-word detector 554 detects a wake word, a network microphone device may process voice input contained in the received audio. Example wake word detection algorithms accept audio as input and provide an indication of whether a wake word is present in the audio. Many first- and third-party wake word detection algorithms are known and commercially available. For instance, operators of a voice service may make their algorithm available for use in third-party devices. Alternatively, an algorithm may be trained to detect certain wake words. If the wake-word detector 554 does not detect a wake word, in some embodiments the received audio is discarded, deleted, or overwritten from the lookback buffer 560 after a predetermined time interval (e.g., after 1 second, after 2 seconds, etc.). For example, in some embodiments, the buffer can continuously overwrite the information that is stored in the lookback buffer 560, such as in a ring buffer.

In some embodiments, the wake-word detector 554 runs multiple wake word detections algorithms on the received audio simultaneously (or substantially simultaneously). As noted above, different voice services (e.g. AMAZON's ALEXA®, APPLE's SIRI®, or MICROSOFT's CORTANA®) each use a different wake word for invoking their respective voice service. To support multiple services, the wake word detector 554 may run the received audio through the wake word detection algorithm for each supported voice service in parallel. In such embodiments, the network microphone device 103 may include VAS selector components 556 configured to pass voice input to the appropriate voice assistant service. In other embodiments, the VAS selector components 556 may be omitted.

In some embodiments, a network microphone device may include speech processing components 555 configured to further facilitate voice processing, such as by performing voice recognition trained to a particular user or a particular set of users associated with a household. Voice recognition software may implement voice-processing algorithms that are tuned to specific voice profile(s).

The microphone evaluator components 562 are configured to analyze received audio signals (e.g., those temporarily stored in the lookback buffer 560) to obtain microphone performance data. As noted above, the microphones 224 can include a plurality of microphones arranged in an array. The microphone performance data can include, for example, frequency response data for individual microphones of the array. The frequency response data can be a windowed average in predefined bands over a desired range, for example, a time windowed average in dB SPL (sound pressure level) in third-octave bands between 100 Hz and 8 kHz. Additionally or alternatively, the microphone performance data can include: (1) an echo return loss enhancement measure (i.e., a measure of the effectiveness of the acoustic echo canceller (AEC) for each microphone), (2) a voice direction measure obtained from each microphone; (3) arbitration statistics (e.g., signal and noise estimates for the beam forming streams associated with different microphones); and/or (4) speech spectral data (i.e., frequency response evaluated on processed audio output after acoustic echo cancellation and beamforming have been performed).

The microphone evaluator components 562 can, in some embodiments, perform additional calculations on the obtained microphone data, such as calculating a median frequency response, mean frequency response, or other such averaged value, as well as calculating a range of deviation beyond which microphone performance can be considered aberrant. For example, the microphone evaluator components 562 can calculate a median absolute deviation and identify any individual microphones whose frequency response deviates from the median by some threshold amount (e.g., for more than 75% of the spectrum, the frequency response deviates from the median by more than two times the median absolute deviation). In some embodiments, some or all of the calculations performed on the microphone data are performed on one or more remote computing devices, as described in more detail below.

In some embodiments, one or more of the components 551-556, 560, and 562 described above can operate in conjunction with the microphone(s) 224 to detect and store a user's voice profile, which may be associated with a user account of the media playback system 100. In some embodiments, voice profiles may be stored as and/or compared to variables stored in [a] set of command information, or data table 590, as shown in FIG. 5A. The voice profile may include aspects of the tone or frequency of user's voice and/or other unique aspects of the user such as those described in previously referenced U.S. patent application Ser. No. 15/438,749.

In some embodiments, one or more of the components 551-556, 560, and 562 described above can operate in conjunction with the microphone array 524 to determine the location of a user in the home environment and/or relative to a location of one or more of the NMDs 103. Techniques for determining the location or proximity of a user may include or more techniques disclosed in previously referenced U.S. patent application Ser. No. 15/438,749, U.S. Pat. No. 9,084,058 filed Dec. 29, 2011, and titled “Sound Field Calibration Using Listener Localization,” and U.S. Pat. No. 8,965,033 filed Aug. 31, 2012, and titled “Acoustic Optimization.” U.S. patent application Ser. No. 15/438,749, U.S. Pat. Nos. 9,084,058, and 8,965,033 are incorporated herein by reference in their entirety.

FIG. 5B is a diagram of an example voice input in accordance with aspects of the disclosure. The voice input may be captured by a network microphone device, such as by one or more of the NMDs 103 shown in FIG. 1. The voice input may include a wake word portion 557 a and a voice utterance portion 557 b (collectively “voice input 557”). In some embodiments, the wake word 557 a can be a known wake word, such as “Alexa,” which is associated with AMAZON's ALEXA®). In other embodiments, the voice input 557 may not include a wake word.

In some embodiments, a network microphone device may output an audible and/or visible response upon detection of the wake word portion 557 a. Additionally or alternately, a network microphone device may output an audible and/or visible response after processing a voice input and/or a series of voice inputs (e.g., in the case of a multi-turn request).

The voice utterance portion 557 b may include, for example, one or more spoken commands 558 (identified individually as a first command 558 a and a second command 558 b) and one or more spoken keywords 559 (identified individually as a first keyword 559 a and a second keyword 559 b). A keyword may be, for example, a word in the voice input identifying a particular device or group in the media playback system 100. As used herein, the term “keyword” may refer to a single word (e.g., “Bedroom”) or a group of words (e.g., “the Living Room”). In one example, the first command 557 a can be a command to play music, such as a specific song, album, playlist, etc. In this example, the keywords 559 may be one or more words identifying one or more zones in which the music is to be played, such as the Living Room and the Dining Room shown in FIG. 1. In some examples, the voice utterance portion 557 b can include other information, such as detected pauses (e.g., periods of non-speech) between words spoken by a user, as shown in FIG. 5B. The pauses may demarcate the locations of separate commands, keywords, or other information spoke by the user within the voice utterance portion 557 b.

In some embodiments, the media playback system 100 is configured to temporarily reduce the volume of audio content that it is playing while detecting the wake word portion 557 a. The media playback system 100 may restore the volume after processing the voice input 557, as shown in FIG. 5B. Such a process can be referred to as ducking, examples of which are disclosed in previously referenced U.S. patent application Ser. No. 15/438,749.

f. Example Network and Remote Computing Systems

FIG. 6 is a functional block diagram showing additional details of the remote computing device(s) 105 in FIG. 1. In various embodiments, the remote computing device(s) 105 may receive voice inputs from one or more of the NMDs 103 over the WAN 107 shown in FIG. 1. For purposes of illustration, selected communication paths of the voice input 557 (FIG. 5B) are represented by arrows in FIG. 6. In one embodiment, the voice input 557 processed by the remote computing device(s) 105 may include the voice utterance portion 557 b (FIG. 5B). In another embodiment, the processed voice input 557 may include both the voice utterance portion 557 b and the wake word 557 a (FIG. 5B).

The remote computing device(s) 105 includes a system controller 612 comprising one or more processors, an intent engine 602, and a memory 616. The memory 616 may be a tangible computer-readable medium configured to store instructions executable by the system controller 612 and/or one or more of the playback, network microphone, and/or controller devices 102-104.

The intent engine 662 may receive a voice input after it has been converted to text by a text-to-speech engine (not shown). In some embodiments, the text-to-speech engine is a component that is onboard an individual remote computing device 105 or located at or distributed across one or more other computing devices, such the remote computing devices 105 and/or a network microphone device. The intent engine 662 is configured to process a voice input and determine an intent of the input. In some embodiments, the intent engine 662 may be a subcomponent of the system controller 612. The intent engine 662 is configured to determine if certain command criteria are met for particular command(s) detected in a voice input. Command criteria for a given command in a voice input may be based, for example, on the inclusion of certain keywords within the voice input.

In addition or alternately, command criteria for given command(s) may involve detection of one or more control state and/or zone state variables in conjunction with detecting the given command(s). Control state variables may include, for example, indicators identifying a level of volume, a queue associated with one or more device(s), and playback state, such as whether devices are playing a queue, paused, etc. Zone state variables may include, for example, indicators identifying which, if any, zone players are grouped. The command information may be stored in memory of e.g., the databases 664 and or the memory 216 of the network microphone device. The intent engine 662 may interact with one or more database(s), such as one or more VAS database(s) 664, to process voice inputs. The VAS database(s) 664 may reside in the memory 616 or elsewhere, such as in memory of one or more of the playback, network microphone, and/or controller devices 102-104. In some embodiments, the VAS database(s) 664 may be updated for adaptive learning and feedback based on the voice input processing. The VAS database(s) 664 may store various user data, analytics, catalogs, and other information for NLU-related and/or other processing.

The remote computing device(s) 105 may exchange various feedback, information, instructions, and/or related data with the various playback, network microphone, and/or controller devices 102-104 of the media playback system 100. Such exchanges may be related to or independent of transmitted messages containing voice inputs. In some embodiments, the remote computing device(s) 105 and the media playback system 100 may exchange data via communication paths as described herein and/or using a metadata exchange channel as described in previously referenced U.S. patent application Ser. No. 15/438,749.

Processing of a voice input by devices of the media playback system 100 may be carried out at least partially in parallel with processing of the voice input by the remote computing device(s) 105. Additionally, speech/text conversion components may convert responses from the remote computing device(s) 105 to speech for playback as audible output via one or more speakers when received by an associated playback or network microphone device.

In accordance with various embodiments of the present disclosure, the remote computing device(s) 105 carry out functions of the first VAS 160 for the media playback system 100. FIG. 7A is schematic diagram of an example network system 700 that comprises the first VAS 160. As shown, the remote computing device(s) 105 are coupled to the media playback system 100 via the WAN 107 (FIG. 1) and/or a LAN 706 connected to the WAN 107. In this way, the various playback, network microphone, and controller devices 102-104 of the media playback system 100 may communicate with the remote computing device(s) 105 to invoke functions of the first VAS 160.

The network system 700 further includes additional first remote computing device(s) 705 a (e.g., cloud servers) and second remote computing device(s) 705 b (e.g., cloud servers). The second remote computing device(s) 705 b may be associated with a media service provider 767, such as SPOTIFY® or PANDORA®. In some embodiments, the second remote computing device(s) 705 b may communicate directly the computing device(s) of the first VAS 160. Additionally or alternately, the second remote computing device(s) 705 b may communicate with the media playback system 100 and/or other intervening remote computing device(s).

The first remote computing device(s) 705 a may be associated with a remote evaluator 760. The remote evaluator 760 can be a remote service configured to evaluate microphone performance data obtained over the network (e.g., LAN 706) to identify aberrant or defective microphones and/or to suggest appropriate corrective action.

The computing system 700 can also include remote computing device(s) associated with a second VAS (not shown). The second VAS may be a traditional VAS provider associated with, e.g., AMAZON's ALEXA®, APPLE's SIRI®, MICROSOFT's CORTANA®, or another VAS provider. Although not shown for purposes of clarity, the network computing system may further include remote computing devices associated with one or more additional VASes, such as additional traditional VASes. In such embodiments, media playback system 100 may be configured to select the first VAS 160 over another VAS.

FIG. 7B is a message flow diagram illustrating various data exchanges in the network computing system 700 of FIG. 7A. The media playback system 100 captures a voice input via a network microphone device (block 771), such as via one or more of the NMDs 103 shown in FIG. 1. The media playback system 100 may select an appropriate VAS based on processing criteria stored, e.g., in the data table 590 (blocks 771-773), as described below.

The media playback system 100 may transmit microphone performance data 781 (e.g., microphone performance data obtained via the microphone evaluator components 562 of the NMD 103) to the remote evaluator 760 for processing. The microphone performance data 781 can be, for example, frequency response data for individual microphones of the NMD 103. This microphone performance data 781 can be based on audio detected prior to, during, or subsequent to detection of a trigger event such as a wake word. The microphone performance data 781 can include additional information, such as software version, household ID, serial number of the NMD, etc. In some embodiments, the microphone performance data 781 is provided in a manner that renders the underlying audio content on which it is based indecipherable by the evaluator 760. As such, the media playback system 100 can send microphone performance data 781 to the remote evaluator 760 without exposing the underlying audio content such as the voice utterance or any specific background sounds captured by the microphones.

In cases in which the system 100 can select among different VASes, the remote evaluator 760 can analyze the microphone data 781 in parallel with any additional steps being performed by the media playback system 100 and/or the first VAS 160. For example, a network microphone device may determine a particular VAS to which the voice input should be sent if the media playback system 100 is configured to select a VAS from multiple VASes as shown in the illustrated example, while the remote evaluator 760 can concurrently evaluate the microphone data 781 to identify one or more defective microphones as described in more detail below. In some embodiments, the remote evaluator 760 can evaluate the microphone data 781 either in real-time as the data is received or the data 781 can be stored and evaluated at a later time.

Based on this evaluation, the remote evaluator 760 can determine a corrective action 786 that is transmitted to the media playback system 100. In some embodiments, the corrective action 786 can be transmitted in real-time as it is determined by the remote evaluator 760, or the corrective action 786 can be stored at the remote evaluator 760 and transmitted at a later time. The corrective action 786 can include instructions to the playback system 100 to discard or disregard audio signals received from an identified aberrant microphone. In another example, the corrective action 786 can include instructions to the media playback system 100 to modify the beamforming algorithms of the associated NMD 103 to at least partially compensate for the identified aberrant microphone. For instance, if it is determined that one microphone is performing sub-optimally, a beamforming algorithm that relies only on 5 input microphones (rather than 6 input microphones) can be used.

Returning to the block 773, if the first VAS 160 is selected, the media playback system 100 transmits one or more messages 782 (e.g., packets) containing the voice input to the VAS 160. The media playback system 100 may concurrently transmit other information to the VAS 160 with the message(s) 782. For example, the media playback system 100 may transmit data over a metadata channel, as described in previously referenced U.S. patent application Ser. No. 15/131,244.

The first VAS 160 may process the voice input in the message(s) 782 to determine intent (block 775). Based on the intent, the VAS 160 may send one or more response messages 783 (e.g., packets) to the media playback system 100. In some instances, the response message(s) 783 may include a payload that directs one or more of the devices of the media playback system 100 to execute instructions (block 776). For example, the instructions may direct the media playback system 100 to play back media content, group devices, and/or perform other functions described below. In addition or alternately, the response message(s) 783 from the VAS 160 may include a payload with a request for more information, such as in the case of multi-turn commands.

In some embodiments, the response message(s) 783 sent from the first VAS 160 may direct the media playback system 100 to request media content, such as audio content, from the media service(s) 667. In other embodiments, the media playback system 100 may request content independently from the VAS 160. In either case, the media playback system 100 may exchange messages for receiving content, such as via a media stream 784 comprising, e.g., audio content.

In some embodiments, the media playback system 100 may receive audio content from a line-in interface on a playback, network microphone, or other device over a local area network via a network interface. Example audio content includes one or more audio tracks, a talk show, a film, a television show, a podcast, an Internet streaming video, among many possible other forms of audio content. The audio content may be accompanied by video (e.g., an audio track of a video) or the audio content may be content that is unaccompanied by video.

In some embodiments, the media playback system 100 and/or the first VAS 160 may use voice inputs that result in successful (or unsuccessful) responses from the VAS for training and adaptive training and learning (blocks 777 and 778). In one example, the intent engine 662 (FIG. 6) may update and maintain training learning data in the VAS database(s) 664 for one or more user accounts associated with the media playback system 100.

III. Examples of Evaluating Microphone Behavior

As noted above, a network device such as NMD 103 can include an array of individual microphones. If one or more of the individual microphones suffers performance issues (e.g., due to microphone defects or due to blockage obstructing the microphone), the functionality of the NMD may be impaired. Problems with one or more of the individual microphones can lead to aberrant audio signals, for example, excess noise, distortion, or other artifacts that can deleteriously affect downstream processing of the audio input. In some embodiments, the system can evaluate the audio input received at individual microphones to determine whether one or more of the microphones are performing sub-optimally. For example, comparing the frequency responses of each microphone in the array can reveal aberrant behavior by one or more of the microphones. Optionally, the NMD can take corrective actions to at least partially compensate for the aberrant microphone(s).

FIG. 8 is a functional flow diagram 800 of an example microphone evaluation in accordance with aspects of the disclosure. The diagram 800 illustrates functions that occur on an NMD 103 as well as functions that can occur remotely, for example, on computing devices associated with the remote evaluator 760. In at least some embodiments, any or all of the functions depicted in flow diagram 800 can be performed on the NMD 103. Beginning with the NMD 103, an array of individual microphones 242 a-242 n receives audio input and provides the audio signals to a lookback buffer in block 803. In various embodiments, the number of microphones 242 a-242 n in the array can vary, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more microphones in the array. The microphones 242 a-242 n can be arranged to detect sound in the environment of the NMD 103. In one example, the microphone(s) 242 a-242 n may be arranged to detect audio from one or more directions relative to the NMD 103. The microphone(s) 242 a-242 n may further be arranged to capture location information of an audio source (e.g., voice, audible sound) and/or to assist in filtering background noise.

The lookback buffer can store the audio signals from the individual microphones 242 a-242 n for a predetermined time interval. For example, in some embodiments the lookback buffer stores the audio signals for less than less than 5 seconds, less than 4 seconds, less than 3 seconds, less than 2 seconds, or less than 1 second, such as overwriting in a buffer.

The audio signals pass from the lookback buffer 560 to audio processing in block 803. The audio processing can combine the audio signals from the individual microphones 242 a-242 n and perform other operations, such as filtering, balancing, etc. The processed audio 803 proceeds to block 805 for event triggering. Here, the NMD 103 can evaluate the processed audio to detect a predetermined trigger event. For example, the trigger event detected in block 807 can be detection of a wake word in the processed audio signal. In some embodiments, the trigger event can take other forms. For example, the trigger event can be the detection of audio signals having some specified property (e.g., detected audio levels above a predetermined threshold, detected audio signals for a predetermined length of time, etc.). If no trigger event is detected in block 805, then the stored audio signals in the lookback buffer 560 can be deleted, discarded, or overwritten and the microphones 242 a-242 n can continue to pass newly acquired audio signals to the lookback buffer 560 until a trigger event is detected in block 805.

If the trigger event is detected in block 805, then the audio signals proceed to device function in block 809. For example, in block 809, one of multiple VASes can be selected, the processed audio can be transmitted to a VAS for further processing, audible output can be provided to a user, instructions can be transmitted to an associated playback device, or any other suitable operation can be carried out following the detection of the trigger event in block 805.

Once the trigger event is detected in block 805, an indication is provided to lookback buffer 560, which can in turn provide the audio signals from the microphones 242 a-242 n for use in calculating microphone performance data in block 809.

The determination of microphone performance data in block 809 can include calculation or collection of any number of parameters associated with the individual microphones. For example, the NMD 103 can evaluate the audio signals obtained from the microphones to obtain performance data such as frequency response data for each microphone. The frequency response data can be a windowed average in predefined bands over a desired range, for example, a time windowed average in dB SPL in third octave bands between 100 Hz and 8 kHz. Additionally or alternatively, the microphone performance data can include (1) an echo return loss enhancement measure (i.e., a measure of the effectiveness of the acoustic echo canceller (AEC) for each microphone), (2) a voice direction measure obtained from each microphone; (3) arbitration statistics (e.g., signal and noise estimates for beamforming associated with each microphone); and/or (4) speech spectral data (i.e., frequency response evaluated on processed audio output after acoustic echo cancellation and beamforming have been performed). The NMD 103 can provide microphone performance data to the remote evaluator 760 for evaluation. To safeguard user privacy, it can be useful to rely only on microphone performance data that does not reveal the original audio content (e.g., the content of recorded speech input). For example, the microphone performance data can be derived from audio content in a manner that renders the original audio signal indecipherable if one only has access to the microphone performance data. This allows the data sent to the remote evaluator 760 to be sufficient to identify aberrant microphones without exposing the actual audio content from which the microphone data is derived.

From block 809, the microphone performance data can be transmitted from the NMD 103 to the remote evaluator 760 for cloud collection in block 811. For example, the remote evaluator 760 can collect microphone performance data from one or more NMDs.

In block 813 the remote evaluator 760 performs population analysis to identify defective or aberrant microphones. In some embodiments, a mean or median value can be calculated for the frequency responses of all the microphones of a given sample for a particular NMD, and the frequency response of each individual microphone can be evaluated against the mean or median value. If the frequency response for any given microphone deviates from the mean or median by more than a threshold amount, then that microphone can be identified as performing sub-optimally. As one example, individual microphones can be identified as aberrant if the frequency response deviates from the median frequency response by more than two times the median absolute deviation per frequency bin for at least 75% of the spectrum. Additionally, the microphone data can be evaluated over time, such that an individual microphone is only flagged as aberrant or malfunctioning if sub-optimal performance has been detected more than some threshold percentage of times. For example, a microphone may be flagged as aberrant if it was performing sub-optimally more than 50% of the time that it has been evaluated over the course of a day.

In some embodiments, the comparison of the microphone performance data (e.g., comparing individual frequency responses against a calculated median for an array of microphones) can be performed locally by the NMD 103. In some embodiments, the microphone performance data is transmitted to the remote evaluator 760, which then compares the microphone performance data to identify aberrant microphones.

The population analysis in block 813 can also evaluate microphone data from a wide range of NMDs, using the aggregate data to improve predictions and analyze corrective suggestions. For example, in block 813, the remote evaluator 760 can analyze aggregate data to identify whether a particular manufacturing batch, a particular model, etc. has an unusually high rate of aberrant microphones, or to identify any other patterns in the presence of aberrant microphone behavior.

In block 815, the remote evaluator 760 can provide corrective suggestions for measures to be taken in response to detecting sub-optimal performance of the one or more individual microphones. For example, the corrective suggestion can instruct the NMD 103 to modify its operation to accommodate the aberrant microphone (e.g., disregarding input from the defective microphone, modifying the beam-forming algorithm to compensate for the defective microphone, etc.). Additionally or alternatively, the NMD 103 can provide an alert to the user, manufacturer, or other entity, potentially with suggested corrective actions (e.g., instructing the user to reposition the device). The alert to the user can be, for example, an audible indication output via speakers 222 (FIG. 2A), or the alert can be a visual indication displayed via the user interface 236 (FIG. 2A). In some embodiments, the alert to the user is provided via the controller device 104, e.g., via user interface(s) 440. In related embodiments, a service code or contact number for contacting a customer service representative can be displayed via the controller device 104 or via the user interface 236 of the playback device 101.

FIGS. 9A-9C illustrate example frequency responses obtained during microphone evaluation of an NMD with six individual microphones in an array. These graphs depict frequency responses for each of six microphones (Spectra 0-5) along with a calculated median value (Median) and a median absolute deviation (Mad). The median can be the median of the six frequency responses, or in some embodiments can be a median of some sub-set of the frequency responses (e.g., a median of five of the six frequency responses if one of the microphones has previously been identified as aberrant). In other embodiments, rather than the median, the mean or other average value can be used. The depicted median absolute deviation (Mad) is a range reflecting the median value plus or minus two times the median absolute deviation. In other embodiments, the Mad can be narrower or wider, for example, extending plus or minus 1 times the median absolute deviation, three times the median absolute deviation, etc. The range depicted by the Mad reflects a range in which microphone performance can be considered normal or typical. As each microphone is generally expected to be exposed to similar conditions and to receive similar input, the frequency output for each microphone is expected to be largely similar for normally-performing microphones. When the frequency response for any microphone extends outside of the Mad range, that may indicate aberrant behavior of that microphone. When the frequency response for a given microphone falls outside of the Mad range by more than some threshold (e.g., more than 25% of the spectrum, more than 50%, more than 75%, etc.), that microphone can be identified as aberrant or as performing sub-optimally. In some embodiments, an array of microphones can be repeatedly evaluated over time, and a microphone may be flagged as aberrant only if it is found to be performing sub-optimally by more than some threshold amount. For example, if a microphone is found to be performing sub-optimally more than 50% of the time, then the microphone can be flagged as aberrant and corrective action may be suggested.

Referring to FIG. 9A, the output of Spectrum 1 indicates a frequency response that falls far above of the median absolute deviation, particularly in lower frequencies. This can indicate aberrant behavior of the microphone associated with Spectrum 1, specifically excess noise resulting in unusually high frequency response from that microphone. This can be due to a defective microphone. In this case, a suggested corrective action may include modifying the audio processing of the NMD to disregard input from that microphone and/or to modify the beamforming algorithm of the device to at least partially compensate for the excess noise detected on the microphone.

FIG. 9B depicts a frequency response chart in which the output of Spectrum 1 falls below the median absolute deviation range. This pattern can indicate an obstruction or other problem leading to a dampened or reduced frequency response of the microphone associated with Spectrum 1 as compared to the other five microphones. For example, a physical obstruction in the microphone port or adjacent to that microphone can lead to a pattern as shown in FIG. 9B. In this instance, a suggested corrective action may include prompting the user to clean the top of the NMD or to reposition the NMD away from any obstructions.

FIG. 9C depicts a frequency response chart in which the output of Spectrum 1 deviates from the median absolute deviation range by falling below the range in lower frequencies and extending above the range in higher frequencies. This pattern can indicate a combination of a defective microphone (leading to excess noise) and an obstruction of the microphone (leading to a reduced frequency response). In this instance, a corrective suggested action may include first prompting a user to clean and/or reposition the device, then further evaluating to determine if the excess noise persists, or instead the corrective suggested action may include modifying the audio processing pipeline of the NMD to disregard input from that microphone and/or to modify the beamforming algorithm of the device to at least partially compensate for the excess noise detected on the microphone.

Although FIGS. 9A-9C depict various frequency response graphs, as noted above, in other embodiments, different parameters other than the frequency response can be used to evaluate and identify aberrant microphone behavior.

FIG. 10 is an example method 1000 of an NMD evaluating individual microphones of an array to detect aberrant behavior. The method 1000 begins at block 1002 with the NMD receiving an audio input at an array of individual microphones. Next, method 1000 advances to block 1004, with the NMD generating output microphone signals from each of the microphones based on the audio input.

In block 1006, the NMD stores the output microphone signals for a predetermined time interval. The output microphone signals can be stored in the lookback buffer 560 (FIG. 5A) or in other memory associated with the NMD. In some embodiments, the output microphone signals can be stored for only the predetermined time interval and then deleted, discarded, or overwritten on a continuous basis. The predetermined time interval can be less than 5 seconds, less than 4 seconds, less than 3 seconds, less than 2 seconds, or less than 1 second, for example being continuously overwritten as in a ring buffer.

Next, the method 1000 continues in block 1008 with analyzing the output microphone signals to detect a trigger event. In some embodiments, the trigger event is the detection of a wake word. The wake word can be detected, for example, via the wake-word detector components 554 (FIG. 5A) as described above. In some embodiments, the trigger event can take other forms. For example, the trigger event can be the detection of audio signals having some specified property (e.g., detected audio volume above a predetermined threshold, detected audio signals for a predetermined length of time, etc.).

After detecting the trigger event, the method 1000 continues in block 1010 with comparing the output microphone signals to detect aberrant behavior of one or more of the microphones. In some embodiments, the output microphone signals can be evaluated by the NMD to obtain microphone performance data. As noted above, the microphone performance data can be, for example, frequency response data. In some embodiments, the microphone performance data can include other measurements, for example echo return loss enhancement, voice direction measures, arbitration statistics, and/or speech spectral data.

The microphone performance data can then be compared across individual microphones to determine whether one or more of the microphones is performing sub-optimally. In some embodiments, this comparison can be done locally on the NMD. In other embodiments, the microphone performance data can be transmitted over a network to a remote evaluator 760 (FIG. 7A), and the remote evaluator can compare the microphone performance data to detect aberrant behavior by one or more of the individual microphones. The comparison can include comparing frequency response data for each microphone and identifying any which deviate from the median frequency response for the array of microphones by more than some threshold amount (e.g., more than 75% of the spectrum deviates from the median frequency response by more than two times the median absolute deviation per frequency bin). In some instances, an individual microphone may only be flagged as aberrant if sub-optimal performance is detected at least some number of times, or if sub-optimal performance is detected during at least some threshold percentage of cases (e.g., if more than 50% of the time the microphone is found to be performing sub-optimally, then the microphone is flagged as aberrant).

In some embodiments, the remote evaluator can perform a population analysis, for example, by comparing the evaluation results of a number of different NMDs to identify trends, improve predictions, or to offer corrective suggestions. Optionally, the corrective suggestion can be transmitted to the NMD.

In some embodiments, the corrective suggestion includes disregarding audio signals from the sub-optimally performing microphone. The corrective suggestion can include modifying the beam-forming algorithm of the NMD to at least partially compensate for the aberrant microphone behavior. For example, the beam former components 551 (FIG. 5A) can be modified based on the detection of aberrant microphone behavior.

In some embodiments, the corrective suggestion includes an indication to a user to adjust the NMD, for example, to wipe the microphone ports or to reposition the NMD. In these instances, the corrective suggestion can include an audio signal to be played back via the NMD to provide an indication to the user to perform the suggested action. For example, the remote evaluator can transmit an audio signal to the NMD to be played back via an associated playback device. When played back, the audio signal can include spoken suggestions, such as “Please clean any obstructions from the top of your device” or “Please reposition your device.” In some embodiments, the corrective suggestion can be transmitted to a manufacturer, supplier, or other entity associated with the NMD. The corrective suggestion can include metrics regarding the presence of defective or sub-optimally performing microphones for particular NMDs. The corrective suggestions can help identify any issues with the manufacturing pipeline that may lead to aberrant microphone behavior.

IV. Conclusion

The description above discloses, among other things, various example systems, methods, apparatus, and articles of manufacture including, among other components, firmware and/or software executed on hardware. It is understood that such examples are merely illustrative and should not be considered as limiting. For example, it is contemplated that any or all of the firmware, hardware, and/or software aspects or components can be embodied exclusively in hardware, exclusively in software, exclusively in firmware, or in any combination of hardware, software, and/or firmware. Accordingly, the examples provided are not the only way(s) to implement such systems, methods, apparatus, and/or articles of manufacture.

The specification is presented largely in terms of illustrative environments, systems, procedures, steps, logic blocks, processing, and other symbolic representations that directly or indirectly resemble the operations of data processing devices coupled to networks. These process descriptions and representations are typically used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. Numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, it is understood to those skilled in the art that certain embodiments of the present disclosure can be practiced without certain, specific details. In other instances, well known methods, procedures, components, and circuitry have not been described in detail to avoid unnecessarily obscuring aspects of the embodiments. Accordingly, the scope of the present disclosure is defined by the appended claims rather than the forgoing description of embodiments.

When any of the appended claims are read to cover a purely software and/or firmware implementation, at least one of the elements in at least one example is hereby expressly defined to include a tangible, non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on, storing the software and/or firmware.

The present technology is illustrated, for example, according to various aspects described below. Various examples of aspects of the present technology are described as numbered examples (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the present technology. It is noted that any of the dependent examples may be combined in any combination, and placed into a respective independent example. The other examples can be presented in a similar manner. Example 1: a method, comprising receiving, an audio input, via a microphone array of a network microphone device, the microphone array comprising a plurality of individual microphones; producing output microphone signals from each of the individual microphones based on the audio input; analyzing the output microphone signals to detect a trigger event; capturing a voice input based on at least one of the output microphone signals; and after detecting the trigger event, comparing the microphone output signals to detect aberrant behavior of one or more of the microphones. Example 2: the method of Example 1, wherein comparing the output microphone signals comprises: sending the output microphone signals to a remote evaluator; and at the remote evaluator, comparing the output microphone signals to detect aberrant behavior of one or more of the microphones. Example 3: the method of Example 2, further comprising sending the output microphone signals to the remote evaluator while capturing the voice input. Example 4: the method of any one of Examples 1-3, wherein capturing the voice input is in response to detecting the trigger event. Example 5: the method of any one of Examples 1-4, wherein comparing the output microphone signals comprises: analyzing a frequency response for each of the microphones; and comparing the frequency responses for each of the microphones. Example 6: The method of Example 5, wherein comparing the frequency responses comprises: determining a mean or median frequency response for each of the microphones; and identifying any microphone for which the frequency response deviates from the mean or median frequency response by more than a threshold amount. Example 7: the method of Example 6, wherein identifying any microphone for which the frequency response deviates from the mean or median frequency response by more than a threshold amount comprises identifying any microphone for which the frequency response is more than 75% outside of the median frequency response plus or minus two median absolute deviations. Example 8: the method of any one of Examples 1-7, further comprising, after detecting the trigger event: receiving additional audio input via the plurality of individual microphones; and passing the additional audio input to one or more computing devices associated with a voice assistant service. Example 9: the method of Examples 1-5, further comprising after detecting the trigger event, outputting an audible indication. Example 10: the method of Examples 1-6, wherein the trigger event comprises detection of a wake word. Example 11: the method of Examples 1-10, wherein the output microphone signals are stored for a predetermined time interval of less than 5 seconds. Example 12: the method of Example 11, further comprising storing the output microphone signals in a buffer, and wherein the output microphone signals are received and stored on a rolling basis for the predetermined time interval. Example 13: the method of any one of Examples 1-12, wherein, in the absence of the trigger event, the output microphone signals are deleted after a predetermined time interval. Example 14: the method of any one of Examples 1-13, further comprising detecting aberrant behavior of one or more of the microphones; and providing an output indicating detection of the aberrant behavior. Example 15: the method of claim 14, wherein providing the output comprises providing a corrective suggestion to a user. Example 16: the method of any one of Examples 1-15, further comprising detecting aberrant behavior of one or more of the microphones; and performing corrective action to at least partially compensate for the aberrant behavior. Example 17: the method of Example 16, wherein the corrective action comprises disregarding received audio signals from the one or more aberrant microphones. Example 18: the method of any one of Examples 16-17, wherein the corrective action comprises adjusting a beamforming algorithm of the network microphone device.

Example 19: a non-transitory computer-readable medium comprising instructions for identifying aberrant microphone behavior, the instructions, when executed by a processor, causing the processor to perform the method of any of Examples 1-18. Example 20: a network microphone device comprising one or more processors; an array of microphones; and a computer-readable medium storing instructions that, when executed by the one or more processors, cause the network microphone device to perform operations comprising the method of any of Examples 1-18. 

1. A method, comprising: receiving an audio input via a microphone array of a network microphone device, the microphone array comprising a plurality of individual microphones; producing output microphone signals from each of the individual microphones based on the audio input; analyzing the output microphone signals to detect a trigger event; capturing a voice input based on at least one of the output microphone signals; and after detecting the trigger event, comparing the output microphone signals to detect aberrant behavior of one or more of the microphones.
 2. The method of claim 1, wherein comparing the output microphone signals comprises: sending the output microphone signals to a remote evaluator; and at the remote evaluator, comparing the output microphone signals to detect aberrant behavior of one or more of the microphones.
 3. The method of claim 2, further comprising sending the output microphone signals to the remote evaluator while capturing the voice input.
 4. The method of claim 1, wherein comparing the output microphone signals comprises: analyzing a frequency response for each of the microphones; and comparing the frequency responses for each of the microphones.
 5. The method of claim 4, wherein comparing the frequency responses comprises: determining a mean or median frequency response for each of the microphones; and identifying any microphone for which the frequency response deviates from the mean or median frequency response by more than a threshold amount.
 6. The method of claim 1, further comprising, after detecting the trigger event: receiving additional audio input via the plurality of individual microphones; and passing the additional audio input to one or more computing devices associated with a voice assistant service.
 7. The method of claim 1, further comprising: detecting aberrant behavior of one or more of the microphones; and performing corrective action to at least partially compensate for the aberrant behavior.
 8. A non-transitory computer-readable medium comprising instructions for identifying aberrant microphone behavior, the instructions, when executed by a processor, causing the processor to perform the following operations: receiving output microphone signals from individual microphones of a network microphone device; analyzing the output microphone signals to detect a trigger event; capturing a voice input based on at least one of the output microphone signals; and after detecting the trigger event, comparing the output microphone signals from each microphone to detect aberrant behavior of one or more of the microphones.
 9. The computer-readable medium of claim 8, wherein comparing the output microphone signals comprises: sending the output microphone signals to a remote evaluator; and at the remote evaluator, comparing the output microphone signals to detect aberrant behavior of one or more of the microphones.
 10. The computer-readable medium of claim 9, wherein the operations further comprise sending the output microphone signals to the remote evaluator while capturing the voice input.
 11. The computer-readable medium of claim 8, wherein comparing the output microphone signals comprises: analyzing a frequency response for each of the microphones; and comparing the frequency responses for each of the microphones.
 12. The computer-readable medium of claim 11, wherein comparing the frequency responses comprises: determining a mean or median frequency response for microphones; and identifying any microphone for which the frequency response deviates from the mean or median frequency response by more than a threshold amount.
 13. The computer-readable medium of claim 8, wherein the operations further comprise, after detecting the trigger event: receiving additional audio input via the plurality of individual microphones; and passing the additional audio input to one or more computing devices associated with a voice assistant service.
 14. The computer-readable medium of claim 8, wherein the operations further comprise: detecting aberrant behavior of one or more of the microphones; and performing corrective action to at least partially compensate for the aberrant behavior.
 15. A network microphone device comprising: one or more processors; a microphone array comprising a plurality of individual microphones; and a computer-readable medium storing instructions that, when executed by the one or more processors, cause the network microphone device to perform operations, the operations comprising: receiving output microphone signals from each of the microphones; analyzing the output microphone signals to detect a trigger event; capturing a voice input based on at least one of the output microphone signals; and after detecting the trigger event, comparing the output microphone signals from each microphone to detect aberrant behavior of one or more of the microphones.
 16. The device of claim 15, wherein comparing the output microphone signals comprises: sending the output microphone signals to a remote evaluator; and at the remote evaluator, comparing the output microphone signals to detect aberrant behavior of one or more of the microphones.
 17. The device of claim 15, wherein the operations further comprise sending the output microphone signals to the remote evaluator while capturing the voice input.
 18. The device of claim 15, wherein comparing the output microphone signals comprises: analyzing a frequency response for each of the microphones; and comparing the frequency responses for each of the microphones.
 19. The device of claim 15, wherein the operations further comprise, after detecting the trigger event: receiving additional audio input via the plurality of individual microphones; and passing the additional audio input to one or more computing devices associated with a voice assistant service.
 20. The device of claim 15, wherein the operations further comprise: detecting aberrant behavior of one or more of the microphones; and performing corrective action to at least partially compensate for the aberrant behavior. 